Contention resolution schemes involve determining which of a plurality of entities gains control of a resource. In communications systems, a variety of resources, e.g., busses, scrambler algorithms, timing, etc., are vied for by more than one communications device. Scramblers are a type of communications devices which alter the data transmitted through a communications facility using a specific scrambling algorithm. The selection of different scrambling algorithms is often required for each communications direction in a bidirectional communications system. Specifically, in such systems, part of the transmitted signal appears as an "echo" in the incoming signal. When it is necessary to eliminate this echo in order to meet performance objectives, each device must include circuitry which is able to distinguish between this echo and the incoming scrambled signal. This, in turn, requires the use of different scrambling algorithms for each communications direction. One technique to fulfill this requirement is to designate the scrambling devices for one of the communications directions as master devices and to designate the scrambling devices for the other communications direction as slave devices. By assigning different scrambling algorithms to master and slave devices, the determination of the master and slave devices, in turn, assures the usage of different scrambling algorithms in each communications direction. Timing control resolution arises in communications systems when there is a need to determine which of a plurality of communications devices provides the master clock from which the other communications devices synchronize or "slave" their internal operations.
A variety of techniques have been used to resolve contention and, in particular, timing control resolution. In one such technique when there is a communications to be coupled between two devices, the master clock is the clock within the device which transmits first. While this technique works satisfactorily in many applications, there are applications where it is impossible for a communications device to determine whether it transmitted first because of the propagation delay between the time a signal is sent by one device and the time it is received by another device. As a result, two communications devices may reach inconsistent views as to which device transmitted first. It would, therefore, be desirable if a contention resolution could be devised which would eliminate these limitations.